can elaborate which java files is depending on spring3? AuthenticationEntryPoint ?

The waffle.spring namespace is dependent on spring. I would start by simply swapping spring-security 3 for spring 2 (ThirdParty/spring and ThirdParty/spring-security) and modifying existing code to work. You can upload that patch - at least people
who want spring2 will be able to get a build. Next would be to produce a change that supports both. I created a
feature request for all of this.